Abstract:
The image quality was degraded by the surface roughness of astronomy imaging applications, and it might be specified in terms of fractional encircled energy. Relationship between the encircled energy and roughness RMS was qualitatively analysed by cosine phase grating model,moreover,the effective transfer function of the surface was built drew on Fourier optical linear systems theory, then the associated angle spread function as well as encircled energy were deduced. For 1 216(1=0.1 nm) far ultraviolet telescope which closed to diffraction limit and in the terms of primary and secondary mirrors roughness RMS were far less than one wavelength, encircled energy versus RMS roughness and autocovariance width could be infered. So resolution error caused by surface roughness was limited in 0.171 5, the manufacturing requirement for mirrors roughness RMS was less than 31 and autocovariance width was longer than one wavelength. It's useful for our manufacturing guiding significance.